Three-dimensional printing for preoperative rehearsal and intraoperative navigation during laparoscopic rectal cancer surgery with left colic artery preservation

BACKGROUND Prior studies have shown that preserving the left colic artery(LCA)during laparo-scopic radical resection for rectal cancer(RC)can reduce the occurrence of anasto-motic leakage(AL),without compromising oncological outcomes.However,anatomical variations in the branches of the inferior mesenteric artery(IMA)and LCA present significant surgical challenges.In this study,we present our novel three dimensional(3D)printed IMA model designed to facilitate preoperative rehearsal and intraoperative navigation to analyze its impact on surgical safety.AIM To investigate the effect of 3D IMA models on preserving the LCA during RC surgery.METHODS We retrospectively collected clinical dates from patients with RC who underwent laparoscopic radical resection from January 2022 to May 2024 at Fuyang People’s Hospital.Patients were divided into the 3D printing and control groups for sta-tistical analysis of perioperative characteristics.RESULTS The 3D printing observation group comprised of 72 patients,while the control group comprised 68 patients.The operation time(174.5±38.2 minutes vs 198.5±49.6 minutes,P=0.002),intraoperative blood loss(43.9±31.3 mL vs 58.2±30.8 mL,P=0.005),duration of hospitalization(13.1±3.1 days vs 15.9±5.6 days,P<0.001),postoperative recovery time(8.6±2.6 days vs 10.5±4.9 days,P=0.007),and the postoperative complication rate(P<0.05)were all significantly lower in the observation group.CONCLUSION Utilization of a 3D-printed IMA model in laparoscopic radical resection of RC can assist surgeons in understanding the LCA anatomy preoperatively,thereby reducing intraoperative bleeding and shortening operating time,demonstrating better clinical application potential.

Intraoperative application of three-dimensional printed guides in total hip arthroplasty: A systematic review

BACKGROUND Acetabular component positioning in total hip arthroplasty(THA)is of key importance to ensure satisfactory post-operative outcomes and to minimize the risk of complications.The majority of acetabular components are aligned freehand,without the use of navigation methods.Patient specific instruments(PSI)and three-dimensional(3D)printing of THA placement guides are increasingly used in primary THA to ensure optimal positioning.AIM To summarize the literature on 3D printing in THA and how they improve acetabular component alignment.METHODS PubMed was used to identify and access scientific studies reporting on different 3D printing methods used in THA.Eight studies with 236 hips in 228 patients were included.The studies could be divided into two main categories;3D printed models and 3D printed guides.RESULTS 3D printing in THA helped improve preoperative cup size planning and post-operative Harris hip scores between intervention and control groups(P=0.019,P=0.009).Otherwise,outcome measures were heterogeneous and thus difficult to compare.The overarching consensus between the studies is that the use of 3D guidance tools can assist in improving THA cup positioning and reduce the need for revision THA and the associated costs.CONCLUSION The implementation of 3D printing and PSI for primary THA can significantly improve the positioning accuracy of the acetabular cup component and reduce the number of complications caused by malpositioning.

Phase II Clinical Study of Three-Dimensional Printed Coplanar Template Combined with CT-Guided Percutaneous Core Needle Biopsy of Pulmonary Nodules in Elderly Patients

Background: As the population age structure gradually ages, more and more elderly people were found to have pulmonary nodules during physical examinations. Most elderly people had underlying diseases such as heart, lung, brain and blood vessels and cannot tolerate surgery. Computed tomography (CT)-guided percutaneous core needle biopsy (CNB) was the first choice for pathological diagnosis and subsequent targeted drugs, immune drugs or ablation treatment. CT-guided percutaneous CNB requires clinicians with rich CNB experience to ensure high CNB accuracy, but it was easy to cause complications such as pneumothorax and hemorrhage. Three-dimensional (3D) printing coplanar template (PCT) combined with CT-guided percutaneous pulmonary CNB biopsy has been used in clinical practice, but there was no prospective, randomized controlled study. Methods: Elderly patients with lung nodules admitted to the Department of Oncology of our hospital from January 2019 to January 2023 were selected. A total of 225 elderly patients were screened, and 30 patients were included after screening. They were randomly divided into experimental group (Group A: 30 cases) and control group (Group B: 30 cases). Group A was given 3D-PCT combined with CT-guided percutaneous pulmonary CNB biopsy, Group B underwent CT-guided percutaneous pulmonary CNB. The primary outcome measure of this study was the accuracy of diagnostic CNB, and the secondary outcome measures were CNB time, number of CNB needles, number of pathological tissues and complications. Results: The diagnostic accuracy of group A and group B was 96.67% and 76.67%, respectively (P = 0.026). There were statistical differences between group A and group B in average CNB time (P = 0.001), number of CNB (1 vs more than 1, P = 0.029), and pathological tissue obtained by CNB (3 vs 1, P = 0.040). There was no statistical difference in the incidence of pneumothorax and hemorrhage between the two groups (P > 0.05). Conclusions: 3D-PCT combined with CT-guided percutaneous CNB can improve the puncture accuracy of elderly patients, shorten the puncture time, reduce the number of punctures, and increase the amount of puncture pathological tissue, without increasing pneumothorax and hemorrhage complications. We look forward to verifying this in a phase III randomized controlled clinical study. .

Three-dimensional(3D) Printing Technology Assisted by Minimally Invasive Surgery for Pubic Rami Fractures

The feasibility of three-dimensional (3D) printing technology cgmbined with minimally invasive surgery in the treatment of pubic rami fractures was explored.From August 2015 to October 2017,a series of 30 patients who underwent surgical stabilization of their anterior pelvic ring (all utilizing the 3D printing technology)by one surgeon at a single hospital were studied.The minimally invasive incisions were made through anterior inferior cilia spine and pubic nodule.Data collected included the operative duration,the blood loss,the damage of the important tissue,the biographic union and therecovery of the function after the operation.Measurements on inlet and outlet pelvic cardiograph were made immediately post-operation and at all follow-up clinic visits.The scores of reduction and function were measured during follow-up.Results showed that the wounds of 30 patients were healed in the first stage,and there was no injury of important structures such as blood vessels and nerves.According to the Matta criteria,excellent effectiveness was obtained in 22 cases and good in 8 cases.According to the functional evaluation criteria of Majeed,excellent effectiveness was obtained in 21 cases and good in 9 cases.It was suggested that the 3D printing technology assisted by minimally invasive surgery can better evaluate the pelvic fracture before operation,which was helpful in plate modeling, and can shorten surgery duration and reduce intraoperative blood loss and complications. The positioning accuracy was improved,and better surgical result was finally achieved.

Application of the Guiding Template Designed by Three-dimensional Printing Data for the Insertion of Sacroiliac Screws:a New Clinical Technique

This study is aimed to explore the clinical application of the guiding template designed by three-dimensional printing data for the insertion of sacroiliac screws.A retrospective study of 7 cases (from July 2016 to December 2016),in which the guiding template printed by the three-dimensional printing technique was used for the insertion of sacroiliac screws of patients with posterior ring injuries of pelvis,was performed.Totally,4 males and 3 females were included in template group,aged from 38to 65years old (mean 50.86±8.90).Of them,5 had sacral fractures (3 with Denis type Ⅰ and 2 with type Ⅱ)and 2 the separation of sacroiliac joint.Guiding templates were firstly made by the three-dimensional printing technique based on the pre-operative CT data. Surgical operations for the stabilization of pelvic ring by applying the guiding templates were carried out.A group of 8 patients with sacroiliac injuries treated by percutaneous sacroiliac screws were analyzed as a control group retrospectively.The time of each screw insertion,volume of intra-operative blood loss,and the exposure to X ray were analyzed and the Matta's radiological criteria were used to evaluate the reduction quality.The Majeed score was used to evaluate postoperative living quality.The visual analogue scale (VAS)was applied at different time points to judge pain relief of coccydynia.All the 7 patients in the template group were closely followed up radiographically and clinically for 14 to 20 months,mean (16.57±2.44)months.Totally 9 sacroiliac screws for the S 1 and S2 vertebra were inserted in the 7 patients.The time length for each screw insertion ranged from 450 to 870 s,mean (690.56±135.68)s,and the number of times of exposure to X ray were 4 to 8,mean (5.78±1.20).The intra-operative blood loss ranged from 45to 120 mL,mean (75±23.32)mL.According to Matta's radiology criteria,the fracture and dislocation reduction were excellent in 6cases and good in 1.The pre-operative VAS score ranged from 5.2 to 8.1,mean (7.13±1.00).The average one-week/six-month post-operative VAS was (5.33±0.78)and (1.33±0.66),respectively (P<0.05 when compared with pre-operative VAS).The 12-month post-operative Majeed score ranged from 86 to 92,mean (90.29±2.21).The three-dimensional printed guiding template for sacroiliac screw insertion,which could significantly shorten the operation time,provide a satisfied outcome of the stabilization of the pelvic ring,and protect doctors and patients from X-ray exposure,might be a practical and valuable new clinical technique.

Use of three-dimensional printing in preoperative planning in orthopaedic trauma surgery: A systematic review and meta-analysis

BACKGROUND With the increasing complexity of surgical interventions performed in orthopaedic trauma surgery and the improving technologies used in threedimensional(3D)printing,there has been an increased interest in the concept.It has been shown that 3D models allow surgeons to better visualise anatomy,aid in planning and performing complex surgery.It is however not clear how best to utilise the technique and whether this results in better outcomes.AIM To evaluate the effect of 3D printing used in pre-operative planning in orthopaedic trauma surgery on clinical outcomes.METHODS We performed a comprehensive systematic review of the literature and a metaanalysis.Medline,Ovid and Embase were searched from inception to February 8,2018.Randomised controlled trials,case-control studies,cohort studies and case series of five patients or more were included across any area of orthopaedic trauma.The primary outcomes were operation time,intra-operative blood loss and fluoroscopy used.RESULTS Seventeen studies(922 patients)met our inclusion criteria and were reviewed.The use of 3D printing across all specialties in orthopaedic trauma surgery demonstrated an overall reduction in operation time of 19.85%[95%confidence intervals(CI):(-22.99,-16.71)],intra-operative blood loss of 25.73%[95%CI:(-31.07,-20.40)],and number of times fluoroscopy was used by 23.80%[95%CI:(-38.49,-9.10)].CONCLUSION Our results suggest that the use of 3D printing in pre-operative planning in orthopaedic trauma reduces operative time,intraoperative blood loss and the number of times fluoroscopy is used.

Three-dimensional printing for heart diseases: clinical application review

Heart diseases remain the top threat to human health,and the treatment of heart diseases changes with each passing day.Convincing evidence shows that three-dimensional(3D)printing allows for a more precise understanding of the complex anatomy associated with various heart diseases.In addition,3D-printed models of cardiac diseases may serve as effective educational tools and for hands-on simulation of surgical interventions.We introduce examples of the clinical applications of different types of 3D printing based on specific cases and clinical application scenarios of 3D printing in treating heart diseases.We also discuss the limitations and clinically unmet needs of 3D printing in this context.

Role of three-dimensional printing and artificial intelligence in the management of hepatocellular carcinoma:Challenges and opportunities

Hepatocellular carcinoma(HCC)constitutes the fifth most frequent malignancy worldwide and the third most frequent cause of cancer-related deaths.Currently,treatment selection is based on the stage of the disease.Emerging fields such as three-dimensional(3D)printing,3D bioprinting,artificial intelligence(AI),and machine learning(ML)could lead to evidence-based,individualized management of HCC.In this review,we comprehensively report the current applications of 3D printing,3D bioprinting,and AI/ML-based models in HCC management;we outline the significant challenges to the broad use of these novel technologies in the clinical setting with the goal of identifying means to overcome them,and finally,we discuss the opportunities that arise from these applications.Notably,regarding 3D printing and bioprinting-related challenges,we elaborate on cost and cost-effectiveness,cell sourcing,cell viability,safety,accessibility,regulation,and legal and ethical concerns.Similarly,regarding AI/ML-related challenges,we elaborate on intellectual property,liability,intrinsic biases,data protection,cybersecurity,ethical challenges,and transparency.Our findings show that AI and 3D printing applications in HCC management and healthcare,in general,are steadily expanding;thus,these technologies will be integrated into the clinical setting sooner or later.Therefore,we believe that physicians need to become familiar with these technologies and prepare to engage with them constructively.

Design and Fabrication of Drug Delivery Devices with Complex Architectures Based on Three-dimensional Printing Technique

A new type of implantable drug delivery devices （ DDD ） with complicated architectures were fubricated by three-dimensional printing technique, employing levofloxacin （LVFX） as a model drug. Processing parameters were optimized in riew of the layer thickness, spucing between printed lines, flow rate of liquid binder and the fast axis speed. The prepared DDD prototype consists of a double-layer structure, of which the upper region is a reservoir system and the lower region is a matrix one. The in vitro release test revealed that LVFX was released in a dual-puse pattern. This DDD may present a new strategy for the prophylaxis and treatment of diseases such as bone infection in the near future.

Magnetic resonance imaging-three-dimensional printing technology fabricates customized scaffolds for brain tissue engineering

Conventional fabrication methods lack the ability to control both macro- and micro-structures of generated scaffolds. Three-dimensional printing is a solid free-form fabrication method that provides novel ways to create customized scaffolds with high precision and accuracy. In this study, an electrically controlled cortical impactor was used to induce randomized brain tissue defects. The overall shape of scaffolds was designed using rat-specific anatomical data obtained from magnetic resonance imaging, and the internal structure was created by computer- aided design. As the result of limitations arising from insufficient resolution of the manufacturing process, we magnified the size of the cavity model prototype five-fold to successfully fabricate customized collagen-chitosan scaffolds using three-dimensional printing. Results demonstrated that scaffolds have three-dimensional porous structures, high porosity, highly specific surface areas, pore connectivity and good internal characteristics. Neural stem cells co-cultured with scaffolds showed good viability, indicating good biocompatibility and biodegradability. This technique may be a promising new strategy for regenerating complex damaged brain tissues, and helps pave the way toward personalized medicine.

A combination of digital design and three-dimensional printing to assist treatment of thoracolumbar compression fractures using percutaneous kyphoplasty

Objective:To evaluate the clinical efficacy of the preoperative digita1 design combined with three dimensional(3D)printing models to assist percutaneous kyphoplasty(PKP)treatment for thoracolumbar compression frac tures.Methods:From January 2018 to August 2020,we obtained data of 99 patients diagnosed thoracolumbar compression fractures.These patients were divided into control group(n=50)underwent traditional PKP surgery,and observation group(n=49)underwent preoperative digital design combined with 3D printing model assisted PKP treatment.The clinical efficacy was evaluated with five parameters,including operation time,number of intraoperative radiographs,visual analogue scale(VAS)score,Cobb Angle change,and high compression rate of injured vertebrae.Results:There were statistically significant differences of operation time and number of intraoperative radio graphs between the two groups(P<0.05).For VAS score,Cobb Angle change and vertebral height compression rate,all of these three parameters were significantly improved when the patients accepted surgery teatment in two groups(P<0.05).However,there were no significant differences between control group and observation group for these three parameters either before or after surgery(P>0.05).Conclusions:Through the design of preoperative surgical guide plate and the application of 3D printing model to guide the operation,the precise design of preoperative surgical puncture site and puncture Angle of the injured vertebra was realized,the number of intraoperative radiographs was reduced,the operation time was shortened and the operation efficiency was improved.

Prenatal diagnosis of isolated lateral facial cleft by ultrasonography and three-dimensional printing:A case report

BACKGROUND Lateral facial clefts are atypical with a low incidence in the facial cleft spectrum.With the development of ultrasonography(US)prenatal screening,such facial malformations can be detected and diagnosed prenatally rather than at birth.Although three-dimensional US(3DUS)can render the fetus'face via 3D reconstruction,the 3D images are displayed on two-dimensional screens without field depth,which impedes the understanding of untrained individuals.In contrast,a 3D-printed model of the fetus'face helps both parents and doctors develop a more comprehensive understanding of the facial malformation by creating more interactive aspects.Herein,we present an isolated lateral facial cleft case that was diagnosed via US combined with a 3D-printed model.CASE SUMMARY A 31-year-old G2P1 patient presented for routine prenatal screening at the 22nd wk of gestation.The coronal nostril-lip section of two-dimensional US(2DUS)demonstrated that the fetus'bilateral oral commissures were asymmetrical,and left oral commissure was abnormally wide.The left oblique-coronal section showed a cleft at the left oral commissure which extended to the left cheek.The results of 3DUS confirmed the cleft.Furthermore,we created a model of the fetal face using 3D printing technology,which clearly presented facial malformations.The fetus was diagnosed with a left lateral facial cleft,which was categorized as a No.7 facial cleft according to the Tessier facial cleft classification.The parents terminated the pregnancy at the 24th wk of gestation after parental counseling.CONCLUSION In the diagnostic course of the current case,in addition to the traditional application of 2D and 3DUS,we created a 3D-printed model of the fetus,which enhanced diagnostic evidence,benefited the education of junior doctors,improved parental counseling,and had the potential to guide surgical planning.

Three-dimensional printing technology for patient-matched instrument in treatment of cubitus varus deformity:A case report

BACKGROUND Recently,medical three-dimensional printing technology(3DPT)has demonstrated potential benefits for the treatment of cubitus varus deformity(CVD)by improving accuracy of the osteotomy through the use of an osteotomy guide,with or without a patient-mated plate.Here,we present an interesting CVD case,involving a patient who was treated with corrective biplanar chevron osteotomy using an innovative customized osteotomy guide and a newly designed patient-matched monoblock crosslink plate created with 3DPT.CASE SUMMARY A 32-year-old female presented with a significant CVD from childhood injury.A computer simulation was processed using images from computerized tomography scans of both upper extremities.The biplanar chevron osteotomy was designed to create identical anatomy between the mirror image of the contralateral distal humerus and the osteotomized distal humerus.Next,the customized osteotomy guide and patient-matched monoblock crosslink plate were designed and printed.A simulation osteotomy was created for the real-sized bone model,and the operation was performed using the posterior paratricipital approach with k-wire positioning from the customized osteotomy guide as a predrilled hole for screw fixation to achieve immediate control of the reduction after osteotomy.Our method allowed for successful treatment of the CVD case,significantly improving the patient’s radiographic and clinical outcomes,with satisfactory result.CONCLUSION 3DPT-created patient-matched osteotomy guide and instrumentation provides accurate control during CVD correction.

Three-dimensional printing in paediatric orthopaedic surgery

Three-dimensional(3D)printing is a rapidly evolving and promising field to improve outcomes of orthopaedic surgery.The use of patient-specific 3D-printed models is specifically interesting in paediatric orthopaedic surgery,as limb deformity corrections often require an individual 3D treatment.In this editorial,various operative applications of 3D printing in paediatric orthopaedic surgery are discussed.The technical aspects and the imaging acquisition with computed tomography and magnetic resonance imaging are outlined.Next,there is a focus on the intraoperative applications of 3D printing during paediatric orthopaedic surgical procedures.An overview of various upper and lower limb deformities in paediatrics is given,in which 3D printing is already implemented,including posttraumatic forearm corrections and proximal femoral osteotomies.The use of patient-specific instrumentation(PSI)or guiding templates during the surgical procedure shows to be promising in reducing operation time,intraoperative haemorrhage and radiation exposure.Moreover,3D-printed models for the use of PSI or patient-specific navigation templates are promising in improving the accuracy of complex limb deformity surgery in children.Lastly,the future of 3D printing in paediatric orthopaedics extends beyond the intraoperative applications;various other medical applications include 3D casting and prosthetic limb replacement.In conclusion,3D printing opportunities are numerous,and the fast developments are exciting,but more evidence is required to prove its superiority over conventional paediatric orthopaedic surgery.

Preparation of Dashanzha Wan by three-dimensional printing

Objective:To use three-dimensional(3D)printing technology to prepare Dashanzha Wan.Methods:The standard formula proportion of Dashanzha Wan was used to prepare printable materials(normally called the ink)for 3D printing,and different doses and shapes of Dashanzha Wan were prepared.Then,the rheological properties,texture characteristics,scanning electron microscopy,and content of ursolic acid were evaluated.Results:Dashanzha Wan ink showed good shear thinning properties,which is very suitable for 3D printing.The printed sample had a beautiful and regular shape with high resolution.Meanwhile,ursolic acid content in 3D-printed Dashanzha Wan aligned with the ursolic acid content shown in the Pharmacopoeia of the People's Republic of China 2020.Conclusion:The 3D-printed Dashanzha Wan has a better texture,and can be shaped into various shapes according to individual needs,which would increase patients’interest when taking medicine.Moreover,3D printing of Dashanzha Wan could be easily integrated into the digital life system,enabling online customization or use at home.This study reveals that 3D printing technology is a promising method for the production of traditional Chinese medicine with personalized appearance,dosage,and texture,which is suitable for a broader population.

Application Status and Prospect of Three-Dimensional Printing Technology in the Field of Medical Devices

Three-dimensional(3D)printing technology belongs to a new manufacturing science and has been widely used in various fields of industry.This article will apply 3D printing technology as its main research topic,with emphasis on its application in the field of medical devices and prospects for contribution.

Color control of the multi-color printing device

Conventional color-printing systems often use inks of three hues, such as CMY, CMYK and CMYKLcLm, but in order to obtain more realistic color reproductions, the ink set of more than three hues has been adopted by some color-printing systems. It is difficult, however, to model the composed color with the multiple inks when the number of the output ink hues exceeds three due to the none-unique mapping between the color spaces of the CIE Lab and the multi-color printing device. In this paper, we propose a fine color-printing method for multi-color printing device with the ink set of more than three hues. The proposed approach has good color expression ability and provides fine control of the printed color. By dividing the output color space into several subspaces, our method allows one-to-one mapping between the standard color space and the multi-color output color space. It has been proved effective when applied to the digital inkjet printer—Mutoh8000.

Effect of navigation endoscopy combined with threedimensional printing technology in the treatment of orbital blowout fractures

●AIM:To explore the combined application of surgical navigation nasal endoscopy(NNE)and three-dimensional printing technology(3DPT)for the adjunctive treatment of orbital blowout fractures(OBF).●METHODS:Retrospective analysis was conducted on the data of patients with OBF who underwent surgical treatment at the Affiliated Eye Hospital of Nanchang University between July 2012 and November 2022.The control group consisted of patients who received traditional surgical treatment(n=43),while the new surgical group(n=52)consisted of patients who received NNE with 3DPT.The difference in therapeutic effects between the two groups was evaluated by comparing the duration of the operation,best corrected visual acuity(BCVA),enophthalmos difference,recovery rate of eye movement disorder,recovery rate of diplopia,and incidence of postoperative complications.●RESULTS:The study included 95 cases(95 eyes),with 63 men and 32 women.The patients’age ranged from 5 to 67y(35.21±15.75y).The new surgical group and the control group exhibited no statistically significant differences in the duration of the operation,BCVA and enophthalmos difference.The recovery rates of diplopia in the new surgical group were significantly higher than those in the control group at 1mo[OR=0.03,95%CI(0.01–0.15),P<0.0000]and 3mo[OR=0.11,95%CI(0.03–0.36),P<0.0000]postoperation.Additionally,the recovery rates of eye movement disorders at 1 and 3mo after surgery were OR=0.08,95%CI(0.03–0.24),P<0.0000;and OR=0.01,95%CI(0.00–0.18),P<0.0000.The incidence of postoperative complications was lower in the new surgical group compared to the control group[OR=4.86,95%CI(0.95–24.78),P<0.05].●CONCLUSION:The combination of NNE and 3DPT can shorten the recovery time of diplopia and eye movement disorder in patients with OBF.

Real-time Three-Dimensional Color Doppler Flow Imaging： An Improved Technique for Quantitative Analysis of Aortic Regurgitation

The recently introduced real-time three-dimensional color Doppler flow imaging （RT-3D CDFI） technique provides a quick and accurate calculation of regurgitant jet volume （RJV） and fraction. In order to evaluate RT-3D CDFI in the noninvasive assessment of aortic RJV and regurgitant jet fraction （RJF） in patients with isolated aortic regurgitation, real-time three-dimensional echocardiographic studies were performed on 23 patients with isolated aortic regurgitation to obtain LV end-diastolic volumes （LVEDV）, end-systolic volumes （LVESV） and RJV, and then RJF could be calculated. The regurgitant volume （RV） and regurgitant fraction （RF） calculated by two-dimensional pulsed Doppler （2D-PD） method served as reference values. The results showed that aortic RJV measured by the RT-3D CDFI method showed a good correlation with the 2D-PD measurements （r= 0.93, Y=0.89X＋ 3.9, SEE= 8.6 mL, P〈0.001 ）; the mean （SD） difference between the two methods was - 1.5 （9.8） mL. % RJF estimated by the RT-3D CDFI method was also correlated well with the values obtained by the 2D-PD method （r=0.88, Y=0.71X＋ 14.8, SEE= 6.4 %, P〈0. 001）; the mean （SD） difference between the two methods was -1.2 （7.9） %. It was suggested that the newly developed RT-3D CDFI technique was feasible in the majority of patients. In patients with eccentric aortic regurgitation, this new modality provides additional information to that obtained from the two-dimensional examination, which overcomes the inherent limitations of two-dimensional echocardiography by depicting the full extent of the jet trajectory. In addition, the RT-3D CDFI method is quick and accurate in calculating RJV and RJF.

Physical model test and application of 3D printing rock-like specimens to laminated rock tunnels

Weak structural plane deformation is responsible for the non-uniform large deformation disasters in layered rock tunnels,resulting in steel arch distortion and secondary lining cracking.In this study,a servo biaxial testing system was employed to conduct physical modeling tests on layered rock tunnels with bedding planes of varying dip angles.The influence of structural anisotropy in layered rocks on the micro displacement and strain field of surrounding rocks was analyzed using digital image correlation(DIC)technology.The spatiotemporal evolution of non-uniform deformation of surrounding rocks was investigated,and numerical simulation was performed to verify the experimental results.The findings indicate that the displacement and strain field of the surrounding layered rocks are all maximized at the horizontal bedding planes and decrease linearly with the increasing dip angle.The failure of the layered surrounding rock with different dip angles occurs and extends along the bedding planes.Compressive strain failure occurs after excavation under high horizontal stress.This study provides significant theoretical support for the analysis,prediction,and control of non-uniform deformation of tunnel surrounding rocks.